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Biomedical subjects

V Blanchette

Publications and source records attributed to V Blanchette.

62 records · Page 4Linked to original sources
PubMed1987

Carrier detection of haemophilia A using DNA markers in families with an isolated affected male.

The carrier status of women in five families with an isolated haemophilia male was assessed by pedigree analysis, coagulation factor assays and DNA markers. In three families, ten women could be given very low risks of being carriers based on DNA analysis. In two of the families the DNA markers identified the mutation as originating in either the maternal or maternal grandfather's germ cell. Combined DNA and coagulation data suggested that the affected male in a third family was a de novo mutation. DNA analysis of the affected male in another family identified a large deletion of the F8 gene which was present in his mother and three sisters, suggesting that the grandmother was a carrier. A combination of coagulation factor data and DNA marker assessment can determine the carrier status of the majority of females in families with isolated affected haemophilia A males.

DNA↗
PubMed1985

Comparative function of centrifugal apheresis devices.

The function of four apheresis devices has been evaluated to obtain comparative data on performance and safety. Granulocyte yields were highest with the CS-3000 with 1.7 X 10(10) cells, but this preparation also contained 4.5 X 10(11) platelets; plateletpheresis gave ranges of 3.4 X 10(11) to 4.5 X 10(11) cells. The amount of blood processed to obtain these yields varied greatly, ranging from 2.4 to 7 liters. Studies done on the donor return line showed no significant effects of the process. Comparative results on the efficacy of plasma exchange showed relatively little red cell contamination with any of these devices, but significant (6.9 X 10(10) platelet removal in the Fenwal bag.

Cell Separation↗
PubMed1985

Evaluation of a simple immunodiffusion technique for quantitation of platelet-associated immunoglobulin G in childhood immune thrombocytopenias.

Platelet-associated IgG (PAIgG) was quantitated in 33 children with immune thrombocytopenia and platelet counts less than 100 X 10(9)/liter using a simple radial immunodiffusion (RID) assay. Elevated PAIgG levels were found in 76% (16/21) of children with acute idiopathic thrombocytopenic purpura (ITP), 88% (7/8) of children with chronic ITP, and all four children studied with systemic lupus erythematosus and thrombocytopenia. Normal PAIgG values were found in children with the following disorders: malignancy and chemotherapy-related thrombocytopenia; ITP in remission (platelet counts greater than 150 X 10(9)/liter); various nonimmune hematologic disorders and juvenile rheumatoid arthritis, these children having normal platelet counts. In children with acute ITP, elevated PAIgG values at initial presentation fell to within the normal range when clinical remission occurred. The RID assay can be easily established in most hematology laboratories and has the advantage that solubilized "test" platelets used in the assay can be stored frozen prior to analysis. We conclude that this simple technique is of value in the evaluation of childhood thrombocytopenic states and yields results comparable to those reported using more complex antiplatelet antibody assays.

Adolescent↗
PubMedDate not supplied

Newly diagnosed idiopathic thrombocytopenic purpura in childhood: an observational study.

BACKGROUND: Diagnosis and management of idiopathic thrombocytopenic purpura (ITP) have been based primarily on expert opinion and practice guidelines rather than on evidence. We have used a registry to prospectively survey the presenting features and the diagnostic evaluation and management practices used for children with ITP worldwide. METHODS: We used the Intercontinental Childhood ITP Registry which had been widely advertised. 209 physicians from 136 institutions in 38 countries participated by submitting data for each of their newly diagnosed patients. Data from 2031 children with ITP was registered between June, 1997, and May, 2000, and we analysed 6-month follow-up data from 1496 children. FINDINGS: There was a peak in occurrence of childhood ITP during spring and a nadir in the autumn. Mean initial platelet count was 15.4x10(9)/L (SD 19.7). 1447 (73%) of 1976 children were admitted to hospital. Initial management consisted of no drug treatment in 612 (31%), intravenous immunoglobulin in 576 (29%), corticosteroids in 651 (33%), or both in 137 (7%) patients. Intracranial haemorrhage was reported in two patients. INTERPRETATION: The variable approaches to management of childhood ITP demonstrate the need for prospective clinical trials, which should be feasible within such a study group.

Adolescent↗
PubMedDate not supplied

A cost-effectiveness evaluation of platelet crossmatching and HLA matching in the management of alloimmunized thrombocytopenic patients.

Effective platelet support for alloimmunized refractory thrombocytopenic patients may be provided by several potential strategies, the most common being HLA-matched single-donor platelets or crossmatch-compatible, pooled random- or single-donor platelets. This study used a detailed economic analysis to compare the cost-effectiveness of several techniques for platelet crossmatching and that of HLA-matched single-donor platelets. The crossmatch methods evaluated were a microlymphocytotoxicity test (LCT), an immunofluorescence technique (PSIFT), a radioactive antiglobulin test (PRAT), and an enzyme-linked immunosorbent assay (ELISA). The analysis was based on the need to support 100 refractory patients with acute leukemia with a presumed requirement of 500 transfusions. The relative costs for a successful crossmatch were: PRAT less than LCT less than LCT + PRAT less than PSIFT less than ELISA. In the comparison of the crossmatch methods, an increase in costs was generally associated with an increase in the number of successful transfusion episodes. However, decreasing marginal gains were seen. The HLA-matched single-donor platelets were relatively cost-inefficient in comparison to the crossmatch-compatible platelets. A theoretic sequence of tests for cost-effective provision of optimal platelet support in refractory patients was evaluated. Such considerations of cost are important in the selection of an optimal program for the management of alloimmunized refractory thrombocytopenic patients.

Blood Platelets↗
PubMedDate not supplied

Induction of a secondary human anti-HLA alloimmune response in severe combined immunodeficient mice engrafted with human lymphocytes.

BACKGROUND: Experimental manipulation of transfusion-induced alloimmunization is limited in humans by ethical considerations. Conversely, studies of alloimmunization in animal models may not reflect the human immune system closely enough to be of optimal benefit. The development of an in vivo model of human alloimmunization that is amenable to experimental manipulation is thus desirable. STUDY DESIGN AND METHODS: An in vivo model of human alloimmunization was evaluated by using mice with severe combined immunodeficiency (SCID). SCID mice underwent gamma-radiation (200 cGy) and received an intraperitoneal injection of human peripheral blood lymphocytes (PBLs) from donors immunized to HLA antigens by prior pregnancy (reconstitution). These Hu [human]-PBL-SCID mice were then challenged with HLA-mismatched PBLs. Alloantibodies were evaluated by flow cytometry and a standard two-stage microlymphocytotoxicity assay. RESULTS: Hu-PBL-SCID mice (n = 22) that were challenged with PBLs expressing the HLA antigens to which the donors had previously been immunized, made significantly more IgM and IgG alloantibodies than did the unchallenged mice. Responses were measurable by 1 week after reconstitution and challenge. Prior treatment of SCID mice with anti-asialo GM1, which depletes murine natural killer cells and macrophages, further increased the alloantibody response of challenged mice. The human alloantibodies generated were specific to the challenge HLA antigens as assessed by microlymphocytotoxicity assay. CONCLUSION: Hu-PBL-SCID mice are a useful model system in which to study and manipulate the induction of secondary human alloimmune responses against cellular HLA class I antigens. This model will be valuable for testing the in vivo effect of novel immunotherapies on the inhibition of the human alloantibody response.

Animals↗
PubMedDate not supplied

Preference-based measurement of health-related quality of life (HRQL) in children with chronic musculoskeletal disorders (MSKDs).

BACKGROUND: Health-related quality of life can be measured by patients' health preferences (utilities or values). No method for measuring health state preferences has been standardized for children with arthritis or other musculoskeletal disorders (MSKDs). Such a method is needed for economic evaluations of current and new pediatric treatments. OBJECTIVES: 1) To assess the feasibility of utility measurements in children with MSKDs, 2) to test the validity of the Health Utility Index (HUI) for these children, 3) to assess whether rating scale values can be mathematically converted into meaningful standard gamble (SG) utilities, and 4) to study whether parents can act as proxies for their children with respect to health state preferences. METHODS: Eighty parents of children with MSKDs were consecutively sampled. Their children, if 8 years of age or older (n = 55), were studied concurrently. Utilities of current health states were obtained by using the SG and the HUI in random order. In addition, health state preferences were assessed using categorical and analog rating scales. Traditional nonutility measures of health status (the Childhood Health Assessment Questionnaire [CHAQ] and the Activities Scale for Kids [ASK]) were also completed. Intraclass correlation coefficients (ICCs) were calculated to assess concordance between the different utility measures and also between the ratings of the parents and their children. RESULTS: Children 8 years of age or older were able to express the strength of their health state preferences using the HUI and rating scales. Children older than 10 years of age were able to use the SG method. The health state utilities of the parents were higher than those of their children. The utilities varied widely depending on the elicitation method. The expected high agreement between the SG and the HUI was not found (ICC = 0.028 for parents, ICC = 0.016 for patients). Unlike the SG, the global utilities derived from the HUI agreed better with preferences derived from rating scales (ICC = 0.23-0.25) and correlated with traditional health status measures (with CHAQ, r = -0.56; with ASK, r = 0.46) both for parents and children. It was not possible to mathematically convert rating scale preferences into SG utilities. The SG utilities were unrelated to results from the rating scales, the CHAQ, and the ASK. Especially for parents, the SG utilities were very high, even when ratings of the other measures indicated poor health. CONCLUSIONS: Although it is possible to measure health utilities for children with MSKDs, the results are highly method dependent. The properties of the HUI in this population are more like those of the traditional health status measures rather than those of the SG. Preferences derived from rating scales, although easily performed, cannot readily be converted into SG utilities. Parents' ratings for their children are impaired by risk aversion.

Adolescent↗